Can I own a trademark and not necessarily use it?
Technically, yes - but I wouldn't encourage it!
Trademarks are vulnerable to removal if they are not used for a period of time, or, if at the time of filing the application the applicant had no intention to use the trademark in good faith.
A trademark may be removed on the above basis by application of a third party - so, if another person/business didn't think you were using your trademark any longer and wanted it off the database they could make an application seeking to remove it. (This would usually occur if someone was trying to register a similar trademark and yours was coming up as a problem for them). (So, technically you could continue to own a trademark without using it because it may be that no-one ever seeks to remove it).
In the above circumstances though, if you ARE still using your trademark or believe you deserve to keep your registration there are options to oppose 'removal applications' so this should be considered and assistance sought.