If you are a "Limitada", you can register as many domains as you need. There is no restriction regarding the amount of domains you can register and no requirement to only register domains that match your company name.
A corporate identifier is the legal form of a company. There are different legal forms around the world. Examples of the most famous include: Ltd. for "Limited", Inc. for "Incorporated" and Ltda. for "Limitada", the latter especially in Latin America.
Only the following characters are allowed for your domain: a-z, A-Z, 0-9 and a hyphen. The length of the Second Level Domain (short SLD) must be between 3 and 63 characters. The SLD is the part of the domain preceding the dot. Example: nic.ltda – "nic" is the SLD and ".ltda" is the TLD.