All ICANN-Accredited Registrars are bound by the same Registrar Accreditation Agreement, which is:
the contract between ICANN and the registrar that governs ICANN’s
relationship with an accredited registrar and the terms and conditions
of maintaining an accreditation.
ICANN-Accredited Registrars also undergo Contractual Compliance audits.
Under this agreement, domain name registrants are provided a list of rights, in which the following is stated:
3.) You shall not be subject to false advertising or deceptive practices by your Registrar or though any proxy or privacy services
made available by your Registrar. This includes deceptive notices,
hidden fees, and any practices that are illegal under the consumer
protection law of your residence.
Providing that you comply with the list of registrant responsibilities, registrars can lose their accreditation if they act in ways that violate your registrant rights, and may be subject to consumer protection laws.
It is highly unlikely that accredited registrars would prevent you from renewing your domain name or arbitrarily sell/transfer it to another party. If that were the case, stories of domain misappropriation would be rampant and well-documented.
It is advisable to register your domain through an ICANN-Accredited Registrar, and not a third-party registering the domain for you (i.e, with their registrant information), otherwise you would not be covered under the registrant rights.
One measure that you can take to maintain the rights to your domain names is to trademark them in the countries under which you're doing business in. Prior usage and rights to the mark may be grounds for successfully filing, or defending against, a UDRP case, especially if you can demonstrate that the other party had no legitimate rights to it or registered it deceptively (i.e., in "bad faith").